THE LAMB-MÖSSBAUER FACTOR OF METAL IRON FOILS AT 4.2K

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Submitted on 1 Jan 1979

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THE LAMB-MÖSSBAUER FACTOR OF METAL IRON FOILS AT 4.2K

H. Vogel, H. Spiering, W. Irler, U. Volland, G. Ritter

To cite this version:

H. Vogel, H. Spiering, W. Irler, U. Volland, G. Ritter. THE LAMB-MÖSSBAUER FACTOR OF METAL IRON FOILS AT 4.2K. Journal de Physique Colloques, 1979, 40 (C2), pp.C2-676-C2-676.

�10.1051/jphyscol:19792234�. �jpa-00218616�

JOURNAL DE PHYSIQUE Colloque C2, suppl6ment au n o 3, Tome 40, mars 1979, page C2-676

THE

LAMB-NOSSBAUER FACTOR OF METAL IRON FOILS AT

H.Voge1, H.Spiering, W. Irler, U. Volland and G. Ritter

Physikalisches I n s t i t u t der Universitat Erlanger-Niirnberg, B. D. R.

Rdsum6.- Le facteur Lamb -~:ssbauer f est d6termin6 pour le fer metallique 1 4.2K. La m6thode consiste

& utiliser trois feuilles df6paisseurs effectives diff6rentes et 2 mesurer le rapport des surfaces

des pics en pr6sence d'un champ magndtique perpendiculaire ou parallel aux feuilles. On obtient ainsi fFE (4,2K) ⁼ 0,93 i: 0,03.

Abstract.- Recently J.P. Williams and J.S. Brooks /I/ published a novel method of determining the

~amb-Mgssbauer factor f of the absorbers. The idea is to get further linear independent equations for f by changing the effective thickness of the same absorber when the polarization of the absorp- tion lines is changed in external magnetic fields. This has been demonstrated on iron foils. They obtained fFe==0.73 at 4.2 K in strong contradiction to fFe=0.92 /2/ calculated from the Debye model with OD=400 K, which has been obtained from the relativistic temperature shift and the resonant absorption in the range 4.2 K-700 K 131. To our feeling the evaluation in /I/ had to be improved to justify the small fFe(4.2 K) value.

We measured three iron foils at 4.2 K (8.7 1, 2x8.7 1, 20 .OO mg Fe/cm2) in large external magnetic fields parallel and normal to the foil. Each foil gives one area ratio for the four line and two for the six line pattern. The ratios yield the value fFe(4.2 K)=0.94?0.04. To obtain this result the non Lorentzian shape of the absorption lines of the thick absorbers, the overlap, and the apparative broadening of our Mijssbauer spectrometer have been taken into account. From the thickness dependence of the total areas the fFe factor could not be closely confined. Therefore we determined the fS fac- tor of the source (90 mCi in Rh) by the absorption area of sodium nitroprusside (SNP). With the powder value fsNp(296 K)=0.359 of Grant et al. /4/ for SNP the f factor become fS(306 K)=0.77 anf fFe(4.2 K)=0.83+0.03. We fitted the Debye model to our measurements of the total absorption area of SNP in the range 13 K-300 K and found fSNp(296 K)=0.394. This value results in fS(306 K)=0.72 and fFe(4.2 K)=0.93t0.03 which is in agreement with the value from the area ratios and from /2/.

References

/I/ Williams, J.M., Brooks, J.S., Nucl. Instrum.

Methods

128

/2/ Stevens, J.G., Stevens, V.E., ~Essbauer Effect Data Index-1971, p.75.

/3/ Preston, R.S., Hanna, S.S., Heberle, H., Phys.

Rev.

128

/4/ Grant, R.W., Housley, R.M.,Gonser, U., Phys. Rev.

178 (1969) 523.

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Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19792234